Materials scientists at the Harvard School of Engineering and Applied Sciences have developed the first macro-scale thin-film solid-oxide fuel cell, potentially serving as a new source of clean energy.

The small size of existing thin films—membranes that must allow ions to pass through—limits their output. But after four years of research, the SEAS team has developed a way to build the miniscule membranes of the cell without sacrificing power performance.

Principle investigator Shriram Ramanathan, associate professor of materials sciences, says that the new SOFCs, presented earlier this week in Nature Nanotechnology, could help distribute energy and potentially serve as portable energy.

“It could be an inexpensive way to fabricate devices affordable for large scale [applications],” Ramanathan said.

The team must now determine, he said, where their SOFC is best applicable.

“We would like to be able to test this type of fuel cells with different fuels, like hydrocarbons or natural gasses and explore the potential for solid oxide fuel cells to become operable,” Ramanathan says.

His research at Harvard has focused on metal oxides, a class of ceramic materials that have electronic and ionic conductive qualities.

His work currently revolves around two separate programs, he says: in addition to his research on ionic conducting oxides for energy conduction, Ramanathan is also working on a new class of computing devices that incorporate phase transitions.

But he says his team’s research required the full four years.

The difficulty, he says, arose in trying “to understand all the things that go into building that device.”

Working with fuel cell chips, the team soon realized how hard it would be to make a practically relevant active area with the thicker membrane.

According to Ramanathan, “initially, we worked on small area devices just to learn about the materials and basic properties of the structures, which gave us a sense of how challenging it would be to scale up.”

Ramanathan says that the future of the new device could mean inexpensive clean energy.

“The cost need not be very large,” he says. “This is why we use inexpensive materials manufactured in inexpensive ways, because it is important to address cost issues and come up with innovative engineering designs that can mitigate additional cost barriers.”

He said his work, a collaboration of students and young scientists, has benefited greatly from the supportive Harvard community.

“It is such a big deal that the faculty encourage this kind of research and want to see this field grow,” he says.